"You have got to wait for the bleeding to settle down and the tissues to repair because there is the risk that the fluid will continue to build up unless you rest it appropriately and give it time to settle down.''

Dr White said Franklin's knee problems could be traced back to when he hyper-extended his knee in the Hawks' qualifying final loss to Geelong in 2011.

Franklin was cleared of structural damage and played in the following week's semi-final against Sydney after suffering bruising and swelling on his knee.

"When you look at it he actually hyper-extended his knee quite badly and I reckon that that's when this cyst developed because it affected all the tissues and the ligaments at the back of the knee,'' Dr White said.

"I think this has become a bit of an issue for him since that time where if he does too much work on it, the fluid builds up and if that gets to a point where it starts interfering with his running the only way to treat that is to rest it.''